As a method of welding a metal, a technique of a friction stir welding method is disclosed (for example, see Patent Document 1 or 2). The friction stir welding method which brings objects to be worked into contact with each other or brings objects to be worked into almost contact with each other to regulate an elongate bonding region, moves a friction stir welding tool inserted into the bonding region while rotating the friction stir welding tool, and welds the objects to be worked by using frictional heat. The friction stir welding method is a welding method which can welds metals such as iron or aluminum alloy to each other but also different materials to each other.
As a friction stir welding method, welding for aluminum and an aluminum alloy each having a relatively low melting point is frequently examined. It is slightly reported that a friction stir welding method is applied by using a metal or an alloy having a high melting point of 1350° C. or more as a high melting point as an object to be worked. However, a technique which welds platinum having a high melting point is disclosed (for example, see Patent Document 3).
Patent Document 1: Japanese Patent Application National Publication (Laid-Open) No. 7-505090
Patent Document 2: Japanese Patent Application National Publication (Laid-Open) No. 9-508073
Patent Document 3: Japanese Patent Application Laid-Open (JP-A) No. 2004-090050